Control of robotic manipulators with flexible joints during constrained motion task execution

The control and stability of manipulators with flexible joints during constrained-motion task execution is investigated. A singular perturbation model that represents the joint flexibility caused by compliance in actuator drive shafts as well as transmission systems is developed. The concept of composite control is used to formulate a control for the slow and fast subsystem dynamics. The slow subsystem control is comprised of a corrective control which uses the concept of an integral manifold to compensate for flexibility effects, in conjunction with a rigid control law, based on the rigid manipulator constrained dynamic equations of motion. With this control applied to the robotic system, it is demonstrated that the high-frequency flexible modes do not destabilize the system. Results of a numerical simulation of a two-joint manipulator during execution of a constrained-motion task are presented to support the analytic results